The phoneme /r/ is one of the five most used English consonants. Its frequency of occurrence in spoken English consonants is approximately 9%. There are several sound variations, called allophones, within the phoneme /r/. The phoneme is considered a consonant when it initiates a syllable (as in the word "red") or when it occurs in a consonant blend (e.g. "dr" as in dress). It is considered vocalic or vowelized when it occurs within a syllable (e.g. bird) or in a postvocalic position (as in water). The symbol for the vowel r is 3.
Difficulty pronouncing r sounds is one of the residual errors most often found in school age children. The persistence of this error may be related to the difficulty of correcting misarticulation of this phoneme. The tongue shape and position when articulating r are not easily visible, which makes it a difficult sound to teach and learn by imitation. Traditional speech therapy, however, has relied almost exclusively on instructional, auditory techniques to teach the phoneme /r/ and other troublesome speech sounds. For example, a clinician will teach a subject auditory discrimination by clarifying the differences between sounds, then may give verbal instruction for reproducing the sound by showing the subject how his mouth and tongue can be used to produce it. The patient will in turn learn to listen carefully to his sound production, and learn to produce the desired sound by imitating the auditory sample, and sometimes the mouth movements, prescribed by the therapist. Teaching r sounds has proven particularly difficult using these methods, particularly after habituation of the error has occurred.
In spite of its drawbacks, most contemporary speech articulation intervention is instructional, and does not rely on instrumentation or appliances to assist in desired sound production. The few speech therapy instruments that have been developed have been so complex that their use has been restricted to laboratories. Chaung and Wang, for example, used a reflected light method to study continuous tongue movements that produce Chinese sounds J. of Speech and Hearing Research 21:482-496 (1978) Barlow and Abbs used force transducers for evaluating labial, lingual and mandibular motor impairments. J. of Speech and Hearing Research 26:616-621 (1983). Siegel and Hanlon studied tactile sensitivity in the mouths of subjects by placing in subjects' mouths a variety of different artificial palates having varying shapes. J. of Speech and Hearing Research 26:574-578 (1983). An orometric system of electro-palatography was used by Fletcher and Hasegawa to set tongue, lip and jaw movements in a deaf child. J. of Speech and Hearing Disorders 48:148-184 (1983). Other methods of electro-palatography have been disclosed by Fletcher, J. of Speech and Hearing Disorders 50:254-261 (1985), Michi et al., J. of Speech and Hearing Disorders 51:226-238 (1986) and in U.S. Pat. Nos. 4,112,596 and 4,334,542.
The complexity of these devices has all limited their therapeutic clinical use. Moreover, these devices have primarily been diagnostic, without providing much therapeutic benefit that directly addresses or treats misarticulation disorders.
It is accordingly an object of the present invention to provide an appliance that facilitates the production of r sounds, particularly the vocalic 3, in human subjects who have difficulty articulating those sounds.
It is another object of the invention to provide such an improved device that is relatively simple and easy to use.
Yet another object is to provide such an improved device that can be simply and inexpensively manufactured.
These and other objects of the invention will be understood more clearly by reference to the following detailed description and drawings.